In a Long Term Evolution-Advanced (LTE-A) mobile communication system of the related art, a CA scheme has been used. The CA scheme is a scheme in which a CC is added in order to increase a data rate without impacting use of a legacy User Equipment (UE), which uses a single carrier. The CA scheme has been applied in the Release 10 version in the LTE mobile communication system, and, for example, the maximum number of CCs used in the CA scheme is five.
However, there is not currently a design for a MOdulator/DE-Modulator (MODEM) that considers the CA scheme.
The CA scheme is divided into an intra-band CA scheme, in which CCs are in the same frequency band, and an inter-band CA scheme, in which the CCs are in different frequency bands according to carrier frequency allocation for each CC. The inter-band CA scheme may be specified into a contiguous CA scheme, in which CCs are in contiguous frequency bands, and a non-contiguous CA scheme, in which the CCs are in non-contiguous frequency bands according to frequency separation among CCs.
Based on frequency usage fairness, network providers are allocated a CC by 5˜10 MHz in the same frequency band. Therefore, the CA scheme is generally implemented with a non-contiguous CA scheme or an inter-band CA scheme rather than an intra-band contiguous CA scheme.
In multi-carrier schemes of the related art, a receiver performs a frequency down conversion operation and a filtering operation based on a center frequency of more than two contiguous bandwidths which have a relatively narrow system bandwidth and performs a filtering operation per frequency bandwidth in an analog domain or a digital domain in order to receive more than two contiguous bandwidths which have the relatively narrow system bandwidth. For example, in the LTE mobile communication system, it should be assumed that a signal of each of contiguous bandwidths is received in the same Node B at the same timing.
However, a CA scheme which is currently considered in the LTE mobile communication system is operated based on signals which are transmitted at different timing points from two Node Bs which are at different locations and have different frequency offsets.
In CA schemes of the related art, multiple channels with contiguous CCs are processed such that it is impossible to properly compensate a frequency offset if a timing point of a signal is changed or a frequency offset is changed. This causes a decrease of transmission/reception performance. Thus, the CA schemes of the related art may not be used if a signal is transmitted/received through an inter-band or an intra-band non-contiguous bandwidth.
Accordingly, a need exists for an improved apparatus and method for processing CA.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.